In recent years light emission efficiency of light-emitting diodes (LEDs) has improved to such an extent that LEDs are attracting attention as a light source for general illumination. In order to drive LEDs, a DC power supply is required.
In consideration of the above, a conventional DC power supply circuit has previously been proposed in order to convert alternating current (AC) supplied by a residential AC power supply, and thereby output DC (refer to Patent Literature 1 and 2). Patent Literature 1 recites a DC power supply circuit which includes a rectifier circuit formed from a diode bridge, a smoothing capacitor connected across output terminals of the rectifier circuit, and a voltage conversion circuit that is connected to an output terminal of the rectifier circuit.